Is there any dull corner of the moon? There are always places with craters that look a lot like each other, but somewhere there are usually oddities and other traits of interest.
The low solar illumination of this great image reveals all kinds of small-scale texture in Janssen. It also suggests that the channel that appears to extend from the main line and curves toward the south edge crosses a dome. Using LOM QuickMap altimetry profiles it is confirmed that there is an increase there, it is about 350 m high and 30 km wide. The texture of the nodosa surface does not resemble a typically smooth sea lava that usually forms domes. It could be sea lava that was bombarded by nearby Fabricius ejecta. Although there is some sea lava about 600 km away at Mare Australe, I doubt that such a lava erupted on Janssen's ground. But the existence of a family of channels on the floor of Janssen has never been well explained. On the QuickMap check I noticed that this small curved channel, about a mile wide, has a much higher north side than the south side, and the last 10 km is not a channel, but rather an escarpment.
Source: Chuck Wood - LPOD